An Analytical Cyclic Steam Stimulation Model for Heavy Oil Reservoirs

Abstract

ABSTRACT The cyclic steam stimulation of wells is of great interest in thermal recovery projects, especially in heavy oil reservoirs where steam injectivity can be achieved without hydraulic fracturing. A number of analytical steam stimulation models have been developed in the past, but no one model can be used for a wide variety of heavy oil reservoirs (i.e. pressure depleted, pressure drive, primary production). A new analytical model for cyclic stimulation of heavy oil reservoirs, which includes pressure drive, has been developed. The model incorporates some of the major recovery mechanisms which are applicable for steam stimulation (i.e. pressure drive, gravity drainage, cold oil influx, relative permeability effects). Simple analytical equations are used to account for the energy and material balance calculations. The model is applicable to both immobile and mobile oil at original reservoir temperatures. The proposed model is a modification and extension of the Gontijo & Aziz model and has additional features beyond the Gozde-AOSTRA model, which include heat loss calculation and wellbore heat losses. The model is validated through a comparison of the results with available field data. A comparison with another analytical model showed that the proposed model is much better equipped to history match a wide variety of heavy oil reservoirs.